In all counties of class one in this state, the assistant prosecuting attorneys shall discharge such duties as may be required of them in criminal and civil causes and in courts having jurisdiction of same on behalf of the state or county; shall attend the grand jury of the county if required so to do by the prosecuting attorney; assist and advise said body; examine witnesses and preserve their testimony. The assistant prosecuting attorneys shall be and are hereby empowered to sign in their own name informations in criminal causes in all courts having jurisdiction in criminal causes.
§ 56.180, RSMo